How to Tell If an Egg Is Still Good?

The quickest check is the float test: place the egg in a bowl of cold water. A fresh egg sinks and lies flat on its side. An egg that floats should be thrown out. If you're still unsure, crack it and smell it — a bad egg is unmistakable.

The float test, step by step:

1. Fill a bowl or glass with enough cold water to cover the egg completely.
2. Gently lower the egg in.
3. Read the result:

Why it works: an eggshell is porous. As an egg ages, moisture and carbon dioxide escape through the shell and air seeps in, growing the air cell at the wide end. More trapped air makes the egg buoyant. So the float test measures age, not bacteria directly.

That's an important limitation: a floating egg isn't necessarily unsafe, and a sinking egg isn't guaranteed safe. Treat the float test as a first screen and confirm with your nose.

The smell test (the definitive one): Crack the egg into a clean bowl — never straight into your other ingredients — and smell it. A spoiled egg gives off a strong sulphurous, rotten smell that is immediately obvious. If it smells like that, throw it out, and wash the bowl. A good egg smells of almost nothing.

The crack test (what to look for after cracking):

• Fresh: the yolk sits high and round, and the white is thick and holds close to the yolk.
• Older but fine: the yolk is flatter and the white spreads out and looks watery. Still perfectly usable, and actually better for hard-boiling and whipping.
• Throw it out: any pink, green, iridescent, or black discolouration in the white or yolk, or a slimy, powdery, or mouldy shell.

Things that look alarming but are fine: a small red or brown speck (a blood spot) is harmless; cloudy white means the egg is very fresh, not spoiled; and stringy white ropes (chalazae) are normal, holding the yolk in place.

How long do eggs last? Refrigerated in their carton, eggs typically stay good for 3–5 weeks past the purchase date, and often beyond the printed date. Hard-boiled eggs last about one week in the fridge.

What the dates mean: "Sell-by," "best-by," and "expiration" dates on egg cartons are quality indicators, not safety cut-offs — eggs are commonly good for weeks after. US cartons may also show a three-digit Julian date (001–365) marking the day they were packed.

Storage that keeps eggs good longer:

• Keep them in the original carton, which limits moisture loss and stops them absorbing fridge odours.
• Store them on a middle shelf, not the door — the door swings through the biggest temperature changes.
• Keep the fridge at or below 40°F (4°C).
• Don't wash eggs before storing. Washing removes the natural protective bloom on the shell.

When in doubt, throw it out — an egg is cheap, and there's no reason to gamble on one you're unsure about. Also discard any egg with a cracked shell, regardless of how it smells.